The Sender Rewriting Scheme preserves .forward functionality in an
SPF-compliant world.
SPF requires the SMTP client IP to match the envelope sender
(return-path). When a message is forwarded through an intermediate
server, that intermediate server may need to rewrite the return-path
to remain SPF compliant. If the message bounces, that intermediate
server needs to validate the bounce and forward the bounce to the
original sender.
This package contains the srs client that can be used in
your .forward files.